97,414 research outputs found

    Strong Cosmic Censorship with Bounded Curvature

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    In this paper we propose a weaker version of Penrose's much heeded Strong Cosmic Censorship (SCC) conjecture, asserting inextentability of maximal Cauchy developments by manifolds with Lipschitz continuous Lorentzian metrics and Riemann curvature bounded in LpL^p. Lipschitz continuity is the threshold regularity for causal structures, and curvature bounds rule out infinite tidal accelerations, arguing for physical significance of this weaker SCC conjecture. The main result of this paper, under the assumption that no extensions exist with higher connection regularity Wloc1,pW^{1,p}_\text{loc}, proves in the affirmative this SCC conjecture with bounded curvature for pp sufficiently large, (p>4p>4 with uniform bounds, p>2p>2 without uniform bounds)

    Weighted bounds for multilinear operators with non-smooth kernels

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    Let TT be a multilinear integral operator which is bounded on certain products of Lebesgue spaces on Rn\mathbb R^n. We assume that its associated kernel satisfies some mild regularity condition which is weaker than the usual H\"older continuity of those in the class of multilinear Calder\'on-Zygmund singular integral operators. In this paper, given a suitable multiple weight w⃗\vec{w}, we obtain the bound for the weighted norm of multilinear operators TT in terms of w⃗\vec{w}. As applications, we exploit this result to obtain the weighted bounds for certain singular integral operators such as linear and multilinear Fourier multipliers and the Riesz transforms associated to Schr\"odinger operators on Rn\mathbb{R}^n. Our results are new even in the linear case

    Solving linear parabolic rough partial differential equations

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    We study linear rough partial differential equations in the setting of [Friz and Hairer, Springer, 2014, Chapter 12]. More precisely, we consider a linear parabolic partial differential equation driven by a deterministic rough path W\mathbf{W} of H\"older regularity α\alpha with 1/3<α≤1/21/3 < \alpha \le 1/2. Based on a stochastic representation of the solution of the rough partial differential equation, we propose a regression Monte Carlo algorithm for spatio-temporal approximation of the solution. We provide a full convergence analysis of the proposed approximation method which essentially relies on the new bounds for the higher order derivatives of the solution in space. Finally, a comprehensive simulation study showing the applicability of the proposed algorithm is presented
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